I guess you use an X100 and probably the F or V (as you're unpacking what's likely a new camera). Both have an optical viewfinder (OVF) as well as an electronic viewfinder (EVF) setting.
Have you been looking through the OVF? If so, there's indeed a very small distortion due to the optics and the magnification factor of the viewfinder. There's also the parallax effect due to the nature of the OVF.
The EVF shows the image as recorded by the sensor and should be free of distortion, although you have of course some perspective distortion when the camera is not exactly horizontal.
